VOL. XV.] BREEDING-HABITS OF MERLIN. 12;J 



myrtillus) are also found. One important factor in the 

 spread of bracken appears to be the method employed in 

 heather burning. If this is left until the ling has passed 

 its prime (eight to ten years' growth) the chances of bracken 

 encroaching on the cleared ground appear to be very great. 

 The extent to which this affects the distribution of the 

 Merlin, which prefers very old heather to any other nesting- 

 site, will be seen below. 



The area comprises a number of well-marked elevations, 

 Burnsall, Thorpe and Cracoe Fell being the three highest' 

 points along the southern and western borders. High ground 

 continues along the eastern edge in the heights known as 

 Crookrise, Embsay and Eastby Crags. The northern edge 

 sinks down into Wharfedale. The majority of streams, 

 therefore, have a north to south flow. 



An examination of a large number of Merlin eyries cannot 

 fail to impress on the observer certain striking similarities 

 which seem never to be wanting. The most characteristic 

 of all is probably the view obtained from the nest. There 

 is the almost invariable valley, to one side, on looking down 

 which one gets an expansive view of rolling moorland and 

 distant fells. (Fig. i.) On looking upstream one generally 

 finds one is near the head of the valley, with the view limited 

 by a hilltop close at hand. More detailed study reveals 

 with regular monotony the proximity of a path, or more 

 occasionally a fence or stone wall. Above the nest there 

 will be as a rule a well " chalked " boulder or two (sometimes 

 a very large number) (Fig. 2), while on the opposite side 

 of the valley, frequently below the level of the eyrie, will 

 be some more boulders evidently in use. The eggs them- 

 selves will in most cases be found in very old heather and 

 there is no doubt that the bird prefers this to anything else. 

 But there is an exception, for the nest may be placed in 

 bracken. This plant is an annual of late appearance and 

 in an average season the only signs of it at the time of nidifica- 

 tion are the desiccated remains of the previous year's growth. 

 As far as I could ascertain the histories of the few bracken 

 areas patronized, they are growths replacing old ling which 

 has been burnt and which had itself harboured an eyrie. 

 During the years intervening between the destruction of the 

 heather and the coming of the bracken. Merlins were absent. 

 These conditions together constitute a typical eyrie and 

 render the finding of the nest in these circumstances merely 

 a matter of a little patience. Atypical eyries seem to differ 

 only in certain respects. The rule that the nest should be 



